For much of its history, the electronics industry has relied on tin-lead solders to make connections in electronic components. Under environmental, competitive, and marketing pressures, the industry is moving to alternative solders that do not contain lead. Pure tin is a preferred alternative solder because of the simplicity of a single metal system, its favorable physical properties, and its proven history as a reliable component of popular solders previously and currently used in the industry. The growth of tin whiskers is a well known but poorly understood problem with pure tin coatings. Tin whiskers may grow between a few micrometers to a few millimeters in length, which is problematic because whiskers may electrically connect multiple features resulting in electrical shorts. The problem is particularly pronounced in high pitch input/output components with closely configured features, such as lead frames and connectors.
Electrical connectors are important features of electrical components used in various applications, such as computers and other consumer electronics. Connectors provide the path whereby electrical current flows between distinct components. Connectors should be conductive, corrosion resistant, wear resistant, and for certain applications solderable. Copper and its alloys have been used as the connector base material because of their conductivity. Thin coatings of tin have been applied to connector surfaces to assist in corrosion resistance and solderability. Tin whiskers in the tin coating present a problem of shorts between electrical contacts.
Accordingly, a need continues to exist for electrical components with a coating that imparts wear resistance, corrosion resistance, and a reduced propensity for whisker growth.